Induction of Thermotolerance in Male Broiler Chickens by Temperature Conditioning at an Early Age

Yahav, S.; Hurwitz, S.

doi:10.3382/ps.0750402

Cited by 199 publications

(119 citation statements)

References 17 publications

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“…In the three experiments, Tb at 7 days of age was reduced by TC as described earlier [11,12] and this reduction remained consistent until the end of the production period, in agreement with earlier findings [3,26,28]. Recent results showed that TC induces the stimulation of gut development and activity, reduces the circulating level of T3 and increases feed intake during the 48 hours following TC [25].…”

Section: Discussionsupporting

confidence: 77%

“…Short periods of intense heat during the dry season in tropical countries induce major economic losses by increasing late mortality of fast growing broiler chickens. Heat exposure at warm ambient temperature (Ta = 36-38 o C) for 24 hours at 5 days of age, a technique described as "early age thermal conditioning" (TC), durably increases the broiler's resistance to heat stress without negative effects on growth and feed conversion [2,3,26,28]. Similar results have been obtained under real and simulated tropical conditions [10,11] in the laboratory and also under practical broiler production in the tropics [9].…”

Section: Introductionsupporting

confidence: 68%

“…A significant reduction of mortality rate has been measured on a large number of broilers at the production level [9]. This difficulty of accurately measuring mortality has led researchers to develop alternative markers of the efficacy of TC such as growth stimulation [13,25,27], variations in circulating T3 level [3,[26][27][28] and body temperature [8,9,16,26,28].…”

Section: Discussionmentioning

confidence: 99%

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Does early thermal conditioning sometimes fail to improve the resistance of broilers to heat stress?

et al. 2002

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-Early age thermal conditioning (TC) by exposing young chicks to 40o C for 24 hours reduces body temperature (Tb) and improves long-term broiler resistance to heat stress. Three experiments were performed under semi-controlled tropical environmental conditions to evaluate the factors affecting TC efficacy. The addition of infrared bulbs during TC reduced growth and increased water intake compared to gas heaters at similar ambient temperatures (Ta). TC consistently reduced the Tb of chickens at 7 and 40 days of age independently of the heat source (-0.22 o C on average). During heat stress after 40 days of age, significant reduction in mortality was observed in the TC chickens when only gas heaters were used in the second experiment. The use of infrared bulbs during the first week of age never resulted in reduced mortality. The third experiment demonstrated late acclimatization when chickens were exposed to natural climatic conditions (Ta varying daily from 26 to 36 o C) compared to maximal Ta limited to 31 o C by air-conditioning from 30 to 40 days of age. Chickens exposed to natural climatic conditions had lower Tb (-0.16 o C) and resisted heat stress at 38 ± 2 o C at 41 days of age, although 12.6% of the air-conditioned chickens died. The TC effects were maintained on Tb in late acclimatized chickens but no differences in mortality due to TC occurred during heat stress. Inconsistencies between TC experiments arise from an imprecise definition of TC and heat stress conditions, and from the environmental conditions perceived by chickens after TC, which can induce late acclimatization. Persistent reductions in Tb after TC have been consistently measured but these might not be directly responsible for resistance to heat stress. Conversely, of the 525 heat stressed chickens studied during the 3 experiments, 64% of those who had a Tb lower than 40.8 o C at 4 days of age (prior to TC exposure) survived heat stress although only 47% of the chicks having a Tb higher than 40.8 o C at 4 days did. Further research is warranted on the Tb of newly hatched chicks. Résumé -L'acclimatation précoce échoue-t-elle parfois à renforcer la résistance des poulets de chair à un stress thermique chaud ? L'acclimatation précoce (TC) qui consiste à exposer des jeunes poussins à 40 o C pendant 24 heures, fait baisser la température corporelle (Tb) et améliore durablement la résistance des poulets de chair à un coup de chaleur. Trois expériences conduites dans un environnement tropical semi-contrôlé évaluent des facteurs de variation de l'efficacité de TC. Par rapport à une source unique de chaleur au gaz pendant TC, l'adjonction d'ampoules infra rouges a diminué la croissance et augmenté la consommation pour une même température ambiante (Ta). Quelle que soit la source de chaleur, Tb mesurée à 7 et 40 jours d'âge, était toujours diminuée par TC (-0,22 o C en moyenne). TC n'a réduit la mortalité pendant un stress thermique après l'âge de 40 jours que lorsqu'il était appliqué avec des éleveuses à gaz au cours de la seconde expérien...

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Section: Discussionsupporting

confidence: 77%

Section: Introductionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

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Does early thermal conditioning sometimes fail to improve the resistance of broilers to heat stress?

et al. 2002

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“…Thermotolerance in birds was achieved by exposing birds to neonatal heat stress (Yahav & Hurwitz 1996). Cyclical higher incubation temperature appears to improve the heat tolerance in chickens (Yahav 2009), depending on the length and period of exposure.…”

Section: Introductionmentioning

confidence: 99%

Effect of increased incubation temperature onHsp90 and 60 gene expressions in coloured broiler chickens

Rajkumar

Vinoth

Shanmugam

et al. 2016

Journal of Applied Animal Research

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The mRNA expression profiles of Hsp-90 alpha, Hsp-90 beta and Hsp-60 were evaluated in coloured broiler chickens, that is, Punjab broiler-2 (PB-2) and naked neck (NN), exposed to 2°C increased incubation temperature for 3 h each on 16th, 17th and 18th days of incubation. Another set of eggs were incubated at normal conditions that were utilized as control. A total of 432 chicks, 216 in each breed (PB-2; NN) and treatment (heat exposed; normal), randomly distributed were reared at high ambient temperatures (32-45°C) during summer in battery brooders. Birds were sacrificed on 0 and 28th days post-hatch and different tissues (heart, liver, muscle, spleen and bursa) were collected to assess the mRNA expression. Heat exposure during incubation significantly (P ≤ .05) influenced the expression of Hsp-90 alpha in spleen of day old; in heart, liver and spleen at 28 days in PB-2 chicken. Hsp-90 alpha mRNA expression was not significant among the tissues at different ages in NN chicken. Hsp-90 beta did not show any significant variations in gene expression across the tissues at both the age groups either in NN or in PB-2 chicken. Heat exposure had significant effect in the expression patterns of Hsp-60 at 28 days in heart, liver and spleen in PB-2 chicken. The mRNA expression of all the three genes significantly (P ≤ .05) varied in different tissues across the age groups in both PB-2 and NN chickens. The study concluded that thermal adaptation during the embryonic stage to higher incubation temperature reduced Hsp gene expression in different tissues in postnatal life during high ambient temperature which might result in increased heat tolerance capacity of the broiler chickens. ARTICLE HISTORY

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“…In broiler chickens, exposure to heat (Arjona et al, 1988;Yahav & Hurwitz, 1996;Yahav, 2000). On the other hand, not much research has been conducted to improve thermotolerance at later ages using prenatal but not postnatal heat conditioning (Moraes et al, 2003;2004;Yalçin et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Effect of short-term pre-hatch heat shock of incubating eggs on subsequent

Şengör¹,

Yardimci²,

Okur³

et al. 2008

SA J. An. Sci.

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________________________________________________________________________________ AbstractThe aim of this study was to investigate the effect of thermal conditioning of broiler chickens during embryonic development on subsequent performance under standard rearing conditions. During incubation eggs from 32-, 45-and 56-week old Ross 308 broiler parent stock were subjected to a 2 h heat shock of 39 °C on days 14 and 15 of incubation. Eggs in the control were incubated throughout incubation at 37 °C. Chicks were feather sexed and equal numbers of each sex were placed in each pen per treatment, and reared for 42 days. Live weight, mortality and feed conversion ratio (FCR) were used as measures of performance. The final (six-week) live weights of broilers from young, mid and older parents for the treatment and control groups were 2113 ± 13.8 vs. 2159 ± 20.0, 2084 ± 29.2 vs. 2139 ± 20.0 and 2096 ± 17.6 vs. 2131 ± 24.3 g, respectively. The six-week live weight of the heat-treated group (2098 ± 12.0 g) was significantly lower than that of the control (2143 ± 12.2 g). The 1-6 week mortality figure was significantly lower in the heat-treated group of chickens from the young (83) and mid parent (77) groups compared to their controls (130 and 119), respectively. However, in the treatment group the incidence of mortality in broilers from the older parent group was significantly higher (105) than that of the control (79). The overall mortality without considering the parent age group was significantly lower in the treatment group (265) than in the control group (328). Mean FCR (g feed/g gain) of the chickens of the three parent groups was 1.79 ± 0.02 vs. 1.75 ± 0.03, 1.85 ± 0.03 vs. 1.77 ± 0.02 and 1.80 ± 0.03 vs. 1.77 ± 0.03 for the treatment vs. control groups, respectively, but the difference was significant only in the mid age parent group. These results suggest that prenatal thermal conditioning is not detrimental to broiler growth under standard rearing conditions in the absence of thermal stress. However, survival rate was improved but live weight and FCR were in some cases significantly poorer. ________________________________________________________________________________

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Induction of Thermotolerance in Male Broiler Chickens by Temperature Conditioning at an Early Age

Cited by 199 publications

References 17 publications

Does early thermal conditioning sometimes fail to improve the resistance of broilers to heat stress?

Does early thermal conditioning sometimes fail to improve the resistance of broilers to heat stress?

Effect of increased incubation temperature onHsp90 and 60 gene expressions in coloured broiler chickens

Effect of short-term pre-hatch heat shock of incubating eggs on subsequent

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